Amend 0.19.3 changelog (#2704)
Amend 0.19.3 changelog (#2704)

* Add past PR to changelog

* Add full breadths of changes since 0.19.1

* Fix link syntax

* Properly format monospace

* Fix wording
mitdbg/modeldb,mitdbg/modeldb,mitdbg/modeldb,mitdbg/modeldb,mitdbg/modeldb